Certain FM radio stations at certain times, or for certain occasions, transmit traffic announcements (road messages) in order to notify drivers of automobiles of congestions, handicaps, detours or points of danger. With an ARI system, it is known to use a pilot signal transmitted from the station to switch on an otherwise switched-off receiver, to switch-off a playing cassette, or to switch over, and in particular, to increase from the actual volume level to a value of volume which is optimum for clear audibility, so that, for example, the driver will have his/her attention drawn to and will not miss the traffic announcement, even with relatively low music volume.
Practical experience has shown that immediately after the switching-over, the traffic announcement is perceived by the driver as unpleasant, is often difficult to understand for acoustic reasons, and may even startle the driver through its suddenly increased volume.
It is the object of the present invention to design a radio receiver for a vehicle in such a way that the spoken announcement is perceived in a subjectively more pleasant way and has improved audibility after the switching-over.
The present invention is based on the following understanding: These days, vehicles such as cars are equipped to an increasing extent with high quality HI-FI radio systems with a stereo cassette player and a multiplicity of loudspeakers. This makes it possible to perform a pleasant HI-FI audio reproduction through respective increasing (emphasizing) of bass and treble which is usually perceived as pleasant. However, for the reproduction of speech, this adjustment is usually less advantageous, especially due to the strongly emphasized bass frequencies. The speech then often sounds dull and can become unintelligible. Now, according to the present invention, on switching-over to traffic announcement, the bass and treble frequencies are also changed, through switching-over the frequency response, to a value which is more subjectively optimum for the respective actual driver and the announcement becomes more pleasant and easier to understand for him/her. It will then no longer be necessary for the driver to manually turn down bass and treble controls. Thus the present invention results in a more pleasant traffic announcement for the driver and an increase in road safety.
The invention-type switching-over of the bass and treble audio frequencies preferably occurs a short time before the switching-over, particularly the increase in volume, for example, in the range of 10 ms in advance. This helps to avoid that the reproduction of the traffic announcement is still unpleasant at the beginning and a crackling noises appear. If desired, along with the above switching-over, further switchings-over in the vehicle can be carried out which are advantageous for the attention of the driver. For example, switching off acoustically disturbing devices such as fans. It may also be useful to switch off the rear loudspeakers in a car upon the switching-over because then the information presented is mainly aimed at the driver and the main objective is clear audibility rather than HI-FI reproduction. Subsequently, the invention is illustrated by means of the drawing using an exemplary embodiment.